Transceiver device

ABSTRACT

A transceiver device includes: a receiving device including a magnetic element having a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, wherein the receiving device is configured to receive an optical signal; a transmission device including a modulated light output element, wherein the transmission device is configured to transmit an optical signal; and a circuit chip including an integrated circuit electrically connected to the magnetic element and the modulated light output element.

BACKGROUND

The present disclosure relates to a transceiver device.

Priority is claimed on Japanese Patent Application No. 2020-178235,filed Oct. 23, 2020, Japanese Patent Application No. 2021-103981, filedJun. 23, 2021, Japanese Patent Application No. 2021-127523, filed Aug.3, 2021, and Japanese Patent Application No. 2021-128190, filed Aug. 4,2021, the content of which is incorporated herein by reference.

Photoelectric conversion elements are used in various applications.

With the spread of the Internet, an amount of communication hasincreased dramatically and the importance of optical communication isincreasing. Optical communication is a communication means configured toconvert an electrical signal into an optical signal and performtransmission and reception using the optical signal.

For example, Patent Document 1 describes a receiving device configuredto receive an optical signal using a photodiode. The photodiode is, forexample, a pn junction diode using a pn junction of a semiconductor orthe like.

PATENT DOCUMENTS

[Patent Document 1] Japanese Unexamined Patent Application, FirstPublication No. 2001-292107

SUMMARY

With the development of information and communication technology, ahigher communication speed is required. In optical communication, higherfrequencies for signal modulation are required. Photodetection elementsusing semiconductor pn junctions are widely used as photoelectricconversion elements, but novel breakthroughs are required for furtherdevelopment.

It is desirable to provide a novel transceiver device.

The following means is provided.

(1) According to a first aspect, there is provided a transceiver deviceincluding: a receiving device including a magnetic element having afirst ferromagnetic layer, a second ferromagnetic layer, and a spacerlayer sandwiched between the first ferromagnetic layer and the secondferromagnetic layer, wherein the receiving device is configured toreceive an optical signal; a transmission device including a modulatedlight output element, wherein the transmission device is configured totransmit an optical signal; and a circuit chip including an integratedcircuit electrically connected to the magnetic element and the modulatedlight output element.

(2) In the transceiver device according to the above-described aspect,the magnetic element and the modulated light output element may bearranged in a direction perpendicular to a surface of the circuit chip.

(3) In the transceiver device according to the above-described aspect, aposition of the circuit chip in the direction is between a position ofthe magnetic element in the direction and a position of the modulatedlight output element in the direction.

(4) In the transceiver device according to the above-described aspect, aposition of the magnetic element in the direction is between a positionof the modulated light output element in the direction and a position ofthe circuit chip in the direction.

(5) In the transceiver device according to the above-described aspect, aposition of the modulated light output element in the direction isbetween a position of the magnetic element in the direction and aposition of the circuit chip in the direction.

(6) In the transceiver device according to the above-described aspect,the magnetic element and the modulated light output element may bepositioned on a first surface side of the circuit chip, and the magneticelement and the modulated light output element may be configured not tooverlap each other when viewed from the direction.

(7) In the transceiver device according to the above-described aspect,the magnetic element and the integrated circuit may be electricallyconnected via first through wiring that passes through an insulatinglayer between the magnetic element and the integrated circuit, and themodulated light output element and the integrated circuit may beelectrically connected via second through wiring that passes through aninsulating layer between the modulated light output element and theintegrated circuit.

(8) In the transceiver device according to the above-described aspect,the modulated light output element and the integrated circuit may beelectrically connected via a bump between the transmission device andthe circuit chip.

(9) The transceiver device according to the above-described aspect mayfurther include a wiring chip including wiring electrically connected tothe magnetic element, the modulated light output element and theintegrated circuit, wherein the magnetic element, the modulated lightoutput element, and the circuit chip may be positioned on a firstsurface side of the wiring chip, and wherein the magnetic element, themodulated light output element, and the circuit chip may be configurednot to overlap each other when viewed from a direction perpendicular toa surface of the wiring chip.

(10) In the transceiver device according to the above-described aspect,the modulated light output element may be an optical modulation element.

(11) In the transceiver device according to the above-described aspect,the optical modulation element may include a waveguide, and thewaveguide may include lithium niobate.

(12) The transceiver device according to the above-described aspect mayfurther include an input portion configured to apply light including asignal to the magnetic element; an output portion configured to outputlight including a signal generated by the modulated light outputelement; a first fiber configured to connect the input portion to anexternal portion; and a second fiber configured to connect the outputportion to an external portion.

The transceiver device according to the above aspect is novel andcreates a novel breakthrough.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual diagram of a communication system according to afirst embodiment.

FIG. 2 is a cross-sectional view of a transmission/reception componentaccording to the first embodiment.

FIG. 3 is a cross-sectional view of a transceiver device according tothe first embodiment.

FIG. 4 is an enlarged cross-sectional view of a feature portion betweena circuit chip and a transmission device according to the firstembodiment.

FIG. 5 is a plan view of a receiving device according to the firstembodiment.

FIG. 6 is a cross-sectional view of a magnetic element according to thefirst embodiment.

FIG. 7 is a diagram for describing a first mechanism of a firstoperation example of the magnetic element according to the firstembodiment.

FIG. 8 is a diagram for describing a second mechanism of the firstoperation example of the magnetic element according to the firstembodiment.

FIG. 9 is a diagram for describing a first mechanism of a secondoperation example of the magnetic element according to the firstembodiment.

FIG. 10 is a diagram for describing a second mechanism of the secondoperation example of the magnetic element according to the firstembodiment.

FIG. 11 is a diagram for describing another second operation example ofthe magnetic element according to the first embodiment.

FIG. 12 is a diagram for describing another second operation example ofthe magnetic element according to the first embodiment.

FIG. 13 is a plan view of an optical modulation element of thetransmission device according to the first embodiment.

FIG. 14 is a cross-sectional view of the optical modulation elementaccording to the first embodiment.

FIG. 15 is a cross-sectional view of a transceiver device according to asecond embodiment.

FIG. 16 is a cross-sectional view of a transceiver device according to athird embodiment.

FIG. 17 is a cross-sectional view of a transceiver device according to afourth embodiment.

FIG. 18 is a plan view of the transceiver device according to the fourthembodiment.

FIG. 19 is a cross-sectional view of a transceiver device according to afifth embodiment.

FIG. 20 is a cross-sectional view of a transceiver device according to asixth embodiment.

FIG. 21 is a plan view of the transceiver device according to the sixthembodiment.

FIG. 22 is a cross-sectional view of another example of the transceiverdevice according to the sixth embodiment.

FIG. 23 is a cross-sectional view of a transceiver device according to aseventh embodiment.

FIG. 24 is a plan view of the transceiver device according to theseventh embodiment.

FIG. 25 is another application example of the communication system.

FIG. 26 is another application example of the communication system.

DETAILED DESCRIPTION

Hereinafter, the present embodiment will be described in detail withreference to the drawings as appropriate. In the drawings used in thefollowing description, featured parts may be enlarged parts forconvenience so that the features of the present disclosure are easier tounderstand, and dimensional ratios and the like of the respectivecomponents may be different from actual ones. Materials, dimensions, andthe like exemplified in the following description are examples, thepresent disclosure is not limited thereto, and modifications can beappropriately made in a range in which advantageous effects of thepresent disclosure are exhibited.

Directions will be defined. A plane on which a substrate 31 constitutinga circuit chip 35 to be described below extends is defined as an xyplane, one direction within the plane is defined as an x direction, anda direction orthogonal to the x direction within the plane is defined asa y direction. Also, a direction orthogonal to the plane on which thesubstrate 31 spreads is defined as a z direction. Hereinafter, a +zdirection may be expressed as an “upward” direction and a −z directionmay be expressed as a “downward” direction. The +z direction is adirection from the substrate 31 to an insulating layer 34. The upwardand downward directions do not always coincide with a direction in whichgravity is applied.

First Embodiment

FIG. 1 is a conceptual diagram of a communication system 200 accordingto a first embodiment. The communication system 200 shown in FIG. 1includes a plurality of transmission/reception components 201 and afiber 202 connected between the transmission/reception components 201.The communication system 200 can be used, for example, for short- andmedium-distance communication within and between data centers, andlong-distance communication between cities. The transmission/receptioncomponent 201 is installed in, for example, a base station or a backbonestation of a long-distance communication network within a data center.For example, the fiber 202 is connected between data centers. Thecommunication system 200 performs communication between thetransmission/reception components 201 via, for example, the fiber 202.In the communication system 200, wireless communication may be performedbetween the transmission/reception components 201 without involving thefiber 202.

FIG. 2 is a cross-sectional view of the transmission/reception component201 according to the first embodiment. The transmission/receptioncomponent 201 includes a transceiver device 100, an input portion 110,an output portion 120, a first fiber 130, a second fiber 140, aconnection portion 150, and a housing 160.

The transmission/reception component 201 is connected to the fiber 202via the connection portion 150. The connection portion 150 is formed inthe housing 160 and is exposed externally.

The first fiber 130 connects the connection portion 150, which isexposed externally, to the input portion 110. The first fiber 130 is,for example, an optical fiber. The input portion 110 is in a travelingdirection of light output from an end of the first fiber 130. The inputportion 110 irradiates the receiving device 15 of the transceiver device100 with light including a signal output from the end of the first fiber130. The input portion 110 is, for example, a mirror, a lens, or thelike. The light transmitted from the fiber 202 to thetransmission/reception component 201 is applied to the receiving device15 via the first fiber 130 and the input portion 110.

The second fiber 140 connects the connection portion 150, which isexposed externally, to the output portion 120. The second fiber 140 is,for example, an optical fiber. The output portion 120 is connected tothe transmission device 25 of the transceiver device 100. The outputportion 120 outputs light including a signal generated by a modulatedlight output element of the transmission device 25. The output portion120 is, for example, a lens or the like. The light output from thetransmission device 25 propagates to the fiber 202 via the outputportion 120 and the second fiber 140.

The transceiver device 100 is stored within the housing 160. Thetransceiver device 100 includes, for example, the receiving device 15,the transmission device 25, and the circuit chip 35. The receivingdevice 15, the transmission device 25, and the circuit chip 35 arelaminated in the z direction.

FIG. 3 is a cross-sectional view of the transceiver device 100 accordingto the first embodiment. The receiving device 15 and the transmissiondevice 25 are arranged on the circuit chip 35 in the z direction. Thereceiving device 15 includes a magnetic element 10. The transmissiondevice 25 includes an optical modulation element 21. The magneticelement 10 and the optical modulation element 21 are arranged on thecircuit chip 35 in the z direction. The circuit chip 35 is positionedbetween the receiving device 15 and the transmission device 25 in the zdirection. A position of the circuit chip 35 in the z direction isbetween a position of the magnetic element 10 in the z direction and aposition of the optical modulation element 21 in the z direction. Forexample, the receiving device 15 (the magnetic element 10) is on a firstsurface 35S1 side of the circuit chip 35 and the transmission device 25(the optical modulation element 21) is on a second surface 35S2 side ofthe circuit chip 35. For example, the receiving device 15 (the magneticelement 10) is arranged on the first surface 35S1 of the circuit chip 35and the transmission device 25 (the optical modulation element 21) isarranged on the second surface 35S2 of the circuit chip 35. The firstsurface 35S1 and the second surface 35S2 are surfaces of the circuitchip 35 facing each other in the z direction.

The receiving device 15 includes, for example, a plurality of magneticelements 10 and an insulating layer 12. Although an example in which thereceiving device 15 has a plurality of magnetic elements 10 is shown inFIG. 3, the number of magnetic elements 10 may be one. The receivingdevice 15 receives an optical signal input from the input portion 110 tothe receiving device 15 and uses the magnetic element 10 to convert thereceived optical signal into an electrical signal. Details of themagnetic element 10 will be described below.

The insulating layer 12 covers the periphery of the magnetic element 10.The insulating layer 12 is, for example, an oxide of Si, Al, or Mg, anitride, or an oxynitride. The insulating layer 12 includes, forexample, silicon oxide (SiO_(x)), silicon nitride (SiN_(x)), siliconcarbide (SiC), chromium nitride, silicon carbonitride (SiCN), siliconoxynitride (SiON), aluminum oxide (Al₂O₃), zirconium oxide (ZrO_(x)) andthe like.

The transmission device 25 includes, for example, an optical modulationelement 21. The transmission device 25 transmits an optical signalmodulated by the optical modulation element 21. The optical modulationelement 21 includes a substrate 22, a coating layer 23, a waveguide 26,and an electrode 27. Details of the optical modulation element 21 willbe described below. The transmission device 25 is attached to thecircuit chip 35 by, for example, an adhesive layer 70.

The circuit chip 35 includes a substrate 31, an electronic component 32,wiring 33, and an insulating layer 34. The circuit chip 35 controlsoperations of the receiving device 15 and the transmission device 25.The substrate 31 is a semiconductor substrate, for example, silicon. Theelectronic component 32 and the wiring 33 are parts of the integratedcircuit 36. The integrated circuit 36 is electrically connected to themagnetic element 10 and the optical modulation element 21. Theelectronic component 32 is, for example, a transistor, a capacitor, orthe like. The wiring 33 is connected between the electronic components32 and the like. The insulating layer 34 is an interlayer insulatinglayer and a material similar to that of the insulating layer 12 can beused therefor. The insulating layer 34 covers the periphery of theelectronic component 32 and the wiring 33.

The magnetic element 10 is provided on the insulating layer 34. Theintegrated circuit 36 (the electronic component 32 or the wiring 33) ofthe circuit chip 35 and the magnetic element 10 of the receiving device15 are electrically connected via, for example, through wiring 50. Thethrough wiring 50 extends in the z direction. The through wiring 50passes through the insulating layer (for example, a part of theinsulating layer 34 or a part of the insulating layer 34 and theinsulating layer 12) between the magnetic element 10 and the integratedcircuit 36 in, for example, the z direction. The through wiring 50connects the magnetic element 10 to the integrated circuit 36 (theelectronic component 32 or the wiring 33).

The integrated circuit 36 of the circuit chip 35 and the opticalmodulation element 21 of the transmission device 25 are electricallyconnected via, for example, through wiring 60. The through wiring 60extends in the z direction. The through wiring 60 passes throughinsulating layers (for example, the substrate 22 having insulatingproperties and the adhesive layer 70) between the optical modulationelement 21 and the integrated circuit 36 in, for example, the zdirection. The through wiring 60 connects the optical modulation element21 to the electronic component 32 or the wiring 33.

The transmission device 25 and the circuit chip 35 sandwiching theadhesive layer 70 may be electrically connected via the bump 63. FIG. 4is an enlarged cross-sectional view of a feature portion between thecircuit chip 35 and the transmission device 25 according to the firstembodiment. The bump 63 connects through wiring 61 passing through thesubstrate 31 of the circuit chip 35 to through wiring 62 passing throughthe substrate 22 of the transmission device 25. The bump 63 is, forexample, solder or the like. The through wiring 61 electrically connectsthe integrated circuit 36 to the bump 63. The through wiring 62electrically connects the optical modulation element 21 to the bump 63.The optical modulation element 21 and the integrated circuit 36 areelectrically connected via the bump 63 between the transmission device25 and the circuit chip 35.

FIG. 5 is a plan view of the receiving device 15 according to the firstembodiment when viewed from the z direction. The receiving device 15converts a state of applied light or a change in the state into anelectrical signal. The receiving device 15 has, for example, a pluralityof magnetic elements 10. Within a spot sp of the applied light, theplurality of magnetic elements 10 may be arranged as shown in FIG. 5 oronly one magnetic element 10 may be arranged.

The light applied to the receiving device 15 is not limited to visiblelight and also includes infrared light having a longer wavelength thanthe visible light and ultraviolet light having a shorter wavelength thanthe visible light. The wavelength of the visible light is, for example,380 nm or more and less than 800 nm. The wavelength of the infraredlight is, for example, 800 nm or more and 1 mm or less. The wavelengthof the ultraviolet light is, for example, 200 nm or more and less than380 nm. The light applied to the receiving device 15 is, for example,light which includes a high-frequency optical signal and whose intensitychanges. The high-frequency optical signal is, for example, a signalhaving a frequency of 100 MHz or more.

When the state of light applied to each of the magnetic elements 10changes, the voltage output from each of the magnetic elements 10 (apotential difference between the ends of each magnetic element in the zdirection) varies with the change in the state of light. FIG. 6 is across-sectional view of the magnetic element 10 according to the firstembodiment. The magnetic element 10 has, for example, a firstferromagnetic layer 1, a second ferromagnetic layer 2, a spacer layer 3,a first electrode 4, and a second electrode 5. The spacer layer 3 ispositioned between the first ferromagnetic layer 1 and the secondferromagnetic layer 2. The magnetic element 10 may have another layer inaddition to the above. The magnetic element 10 is irradiated with lightfrom the first ferromagnetic layer 1 side.

The magnetic element 10 is, for example, a magnetic tunnel junction(MTJ) element in which the spacer layer 3 is made of an insulatingmaterial. In this case, the magnetic element 10 is an element in which aresistance value in the z direction (a resistance value when a currentflows in the z direction) changes in accordance with relative changes ina magnetization state of the first ferromagnetic layer 1 and amagnetization state of the second ferromagnetic layer 2. The aboveelement is also called a magnetoresistance effect element.

The first ferromagnetic layer 1 is a photodetection layer whosemagnetization state changes when light is applied from the outside. Thefirst ferromagnetic layer 1 is also called a magnetization free layer.The magnetization free layer is a layer including a magnet whosemagnetization state changes when a prescribed external force has beenapplied. The prescribed external force is, for example, light appliedfrom the outside, a current flowing through the magnetic element 10 inthe z direction, or an external magnetic field. A state of themagnetization of the first ferromagnetic layer 1 varies with anintensity of light applied to the first ferromagnetic layer 1. Because adirection of the magnetization of a ferromagnet can vary with ahigh-speed change in the intensity of light applied to the ferromagnet(a high-frequency optical signal), the receiving device 15 can convert ahigh-frequency optical signal into an electrical signal using the firstferromagnetic layer 1 as a photodetection layer and high-speed opticalcommunication becomes possible.

The first ferromagnetic layer 1 includes a ferromagnet. In the presentspecification, ferromagnetism includes ferrimagnetism. The firstferromagnetic layer 1 includes at least one of magnetic elements such asCo, Fe, and Ni. The first ferromagnetic layer 1 may include nonmagneticelements such as B, Mg, Hf, and Gd in addition to the above-describedmagnetic elements. The first ferromagnetic layer 1 may be, for example,an alloy including a magnetic element and a nonmagnetic element. Thefirst ferromagnetic layer 1 may include a plurality of layers. The firstferromagnetic layer 1 is, for example, a CoFeB alloy, a laminate inwhich a CoFeB alloy layer is sandwiched between Fe layers, or a laminatein which a CoFeB alloy layer is sandwiched between CoFe layers.

The first ferromagnetic layer 1 may be a perpendicular magnetizationfilm having an axis of easy magnetization in a direction (the zdirection) perpendicular to a film surface even if an in-planemagnetized film has an axis of easy magnetization in an in-planedirection (any direction within an xy plane).

A thickness of the first ferromagnetic layer 1 is, for example, 1 nm ormore and 5 nm or less. A thickness of the first ferromagnetic layer 1may be, for example, 1 nm or more and 2 nm or less. When the firstferromagnetic layer 1 is a perpendicular magnetization film, the effectof applying perpendicular magnetic anisotropy from the layers above andbelow the first ferromagnetic layer 1 is strengthened and theperpendicular magnetic anisotropy of the ferromagnetic layer 1 isincreased if the thickness of the first ferromagnetic layer 1 is thin.That is, when the perpendicular magnetic anisotropy of the firstferromagnetic layer 1 is high, the force for the magnetization to returnin the z direction is strengthened. On the other hand, when thethickness of the first ferromagnetic layer 1 is thick, the effect ofapplying the perpendicular magnetic anisotropy from the layers above andbelow the first ferromagnetic layer 1 is relatively weakened, and theperpendicular magnetic anisotropy of the first ferromagnetic layer 1 isweakened.

A volume of a ferromagnet becomes small when the thickness of the firstferromagnetic layer 1 becomes thin and the volume of the ferromagnetbecomes large when the thickness of the first ferromagnetic layer 1becomes thick. The susceptibility of the magnetization of the firstferromagnetic layer 1 when external energy has been applied is inverselyproportional to a product (KuV) of the magnetic anisotropy (Ku) and thevolume (V) of the first ferromagnetic layer 1. That is, when the productof the magnetic anisotropy of the first ferromagnetic layer 1 and thevolume becomes small, the reactivity to light increases. From this pointof view, in order to enhance the reaction to light, the magneticanisotropy of the first ferromagnetic layer 1 may be appropriatelydesigned and then the volume of the first ferromagnetic layer 1 may bereduced.

When the thickness of the first ferromagnetic layer 1 is thicker than 2nm, an insertion layer made of, for example, Mo and W may be providedwithin the first ferromagnetic layer 1. That is, the first ferromagneticlayer 1 may be a laminate in which the ferromagnetic layer, theinsertion layer, and the ferromagnetic layer are laminated in that orderin the z direction. Interfacial magnetic anisotropy at an interfacebetween the insertion layer and the ferromagnetic layer enhances theperpendicular magnetic anisotropy of the entire first ferromagneticlayer 1. A thickness of the insertion layer is, for example, 0.1 nm to0.6 nm.

The second ferromagnetic layer 2 is a magnetization fixed layer. Themagnetization fixed layer is a layer made of a magnet whosemagnetization state is less likely to change than that of themagnetization free layer when prescribed external energy has beenapplied. For example, in the magnetization fixed layer, a direction ofmagnetization is less likely to change than that in the magnetizationfree layer when prescribed external energy has been applied. Also, forexample, in the magnetization fixed layer, a magnitude of magnetizationis less likely to change than that in the magnetization free layer whenprescribed external energy is applied. For example, coercivity of thesecond ferromagnetic layer 2 is greater than that of the firstferromagnetic layer 1. The second ferromagnetic layer 2 has, forexample, an axis of easy magnetization in the same direction as thefirst ferromagnetic layer 1. The second ferromagnetic layer 2 may beeither an in-plane magnetization film or a perpendicular magnetizationfilm.

For example, the material constituting the second ferromagnetic layer 2is similar to that of the first ferromagnetic layer 1. The secondferromagnetic layer 2 may be, for example, a laminate in which Co havinga thickness of 0.4 nm to 1.0 nm, Mo having a thickness of 0.1 nm to 0.5nm, a CoFeB alloy having a thickness of 0.3 nm to 1.0 nm, and Fe havinga thickness of 0.3 nm to 1.0 nm are laminated in that order.

The magnetization of the second ferromagnetic layer 2 may be fixed by,for example, magnetic coupling to the third ferromagnetic layer via amagnetic coupling layer. In this case, a combination of the secondferromagnetic layer 2, the magnetic coupling layer, and the thirdferromagnetic layer may be called a magnetization fixed layer.

The third ferromagnetic layer is magnetically coupled to, for example,the second ferromagnetic layer 2. The magnetic coupling is, for example,antiferromagnetic coupling and is caused byRuderman-Kittel-Kasuya-Yosida (RKKY) interaction. The materialconstituting the third ferromagnetic layer is, for example, similar tothat of the first ferromagnetic layer 1. The magnetic coupling layer is,for example, Ru, Ir, or the like.

The spacer layer 3 is a nonmagnetic layer arranged between the firstferromagnetic layer 1 and the second ferromagnetic layer 2. The spacerlayer 3 includes a layer made of a conductor, an insulator, or asemiconductor or a layer including a current carrying point formed of aconductor within an insulator. A thickness of the spacer layer 3 can beadjusted in accordance with orientation directions of the magnetizationof the first ferromagnetic layer 1 and the magnetization of the secondferromagnetic layer 2 in an initial state to be described below.

For example, when the spacer layer 3 is made of an insulator, themagnetic element 10 has a magnetic tunnel junction (MTJ) including thefirst ferromagnetic layer 1, the spacer layer 3, and the secondferromagnetic layer 2. Such an element is called an MTJ element. In thiscase, the magnetic element 10 can exhibit a tunnel magnetoresistance(TMR) effect. For example, when the spacer layer 3 is made of a metal,the magnetic element 10 can exhibit a giant magnetoresistance (GMR)effect. Such an element is called a GMR element. The magnetic element 10may be called the MTJ element, the GMR element, or the like, whichdiffers according to the constituent material of the spacer layer 3, butthey may also be collectively called magnetoresistance effect elements.

When the spacer layer 3 is made of an insulating material, materialsincluding aluminum oxide, magnesium oxide, titanium oxide, siliconoxide, and the like can be used. Also, the above insulating materialsmay include elements such as Al, B, Si, and Mg and magnetic elementssuch as Co, Fe, and Ni. A high magnetoresistance change rate can beobtained by adjusting the thickness of the spacer layer 3 so that astrong TMR effect is exhibited between the first ferromagnetic layer 1and the second ferromagnetic layer 2. In order to use the TMR effectefficiently, the thickness of the spacer layer 3 may be about 0.5 to 5.0nm or about 1.0 to 2.5 nm.

When the spacer layer 3 is made of a nonmagnetic conductive material, aconductive material such as Cu, Ag, Au, or Ru can be used. In order touse the GMR effect efficiently, the thickness of the spacer layer 3 maybe about 0.5 to 5.0 nm or about 2.0 to 3.0 nm.

When the spacer layer 3 is made of a nonmagnetic semiconductor material,a material such as zinc oxide, indium oxide, tin oxide, germanium oxide,gallium oxide, or indium tin oxide (ITO) can be used. In this case, thethickness of the spacer layer 3 may be about 1.0 to 4.0 nm.

When a layer including a current carrying point made of a conductorwithin a nonmagnetic insulator is applied as the spacer layer 3, astructure may be formed to include a current carrying point made of anonmagnetic conductor of Cu, Au, Al, or the like within the nonmagneticinsulator made of aluminum oxide or magnesium oxide. Also, the conductormay be made of a magnetic element such as Co, Fe, or Ni. In this case,the thickness of the spacer layer 3 may be about 1.0 to 2.5 nm. Thecurrent carrying point is, for example, a columnar body having adiameter of 1 nm or more and 5 nm or less when viewed from a directionperpendicular to a film surface.

The magnetic element 10 may also have a base layer, a cap layer, aperpendicular magnetization inducing layer, and the like. The base layeris on the lower side of the second ferromagnetic layer 2. The base layeris a seed layer or a buffer layer. The seed layer enhances thecrystallinity of the layer laminated on the seed layer. The seed layeris, for example, Pt, Ru, Hf, Zr, or NiFeCr. A thickness of the seedlayer is, for example, 1 nm or more and 5 nm or less. The buffer layeris a layer that alleviates lattice mismatch between different crystals.The buffer layer is, for example, Ta, Ti, W, Zr, Hf, or a nitride ofthese elements. A thickness of the buffer layer is, for example, 1 nm ormore and 5 nm or less.

The cap layer is on the upper side of the first ferromagnetic layer 1.The cap layer prevents damage to the lower layer during the process andenhances the crystallinity of the lower layer during annealing. Thethickness of the cap layer is, for example, 3 nm or less so that thefirst ferromagnetic layer 1 is irradiated with sufficient light. The caplayer is, for example, MgO, W, Mo, Ru, Ta, Cu, Cr, or a laminated filmthereof.

A perpendicular magnetization inducing layer is formed when the firstferromagnetic layer 1 is a perpendicular magnetization film. Theperpendicular magnetization inducing layer is laminated on the firstferromagnetic layer 1. The perpendicular magnetization inducing layerinduces perpendicular magnetic anisotropy of the first ferromagneticlayer 1. The perpendicular magnetization inducing layer is, for example,magnesium oxide, W, Ta, Mo, or the like. When the perpendicularmagnetization inducing layer is magnesium oxide, magnesium oxide may beoxygen-deficient to increase conductivity. A thickness of theperpendicular magnetization inducing layer is, for example, 0.5 nm ormore and 2.0 nm or less.

A first electrode 4 is in contact with, for example, the surface of thefirst ferromagnetic layer 1 opposite to the spacer layer 3. A secondelectrode 5 is in contact with, for example, the surface of the secondferromagnetic layer 2 opposite to the spacer layer 3. The firstelectrode 4 and the second electrode 5 sandwich the first ferromagneticlayer 1, the second ferromagnetic layer 2, and the spacer layer 3 in thez direction.

The first electrode 4 and the second electrode 5 are made of aconductive material. The first electrode 4 and the second electrode 5are made of, for example, metals such as Cu, Al, Au, and Ru. Ta and/orTi may be laminated on the top and bottom of the above metals. Also, asthe first electrode 4 and the second electrode 5, a laminated film of Cuand Ta, a laminated film of Ta, Cu, and Ti, and a laminated film of Ta,Cu, and TaN may be used. Also, TiN and/or TaN may be used as the firstelectrode and the second electrode.

The first electrode 4 and the second electrode 5 may have transparencywith respect to a wavelength range of light applied to the firstferromagnetic layer 1. For example, the first electrode 4 and the secondelectrode 5 may be transparent electrodes including transparentelectrode materials of oxides such as indium tin oxide (ITO), indiumzinc oxide (IZO), zinc oxide (ZnO), and indium gallium zinc oxide(IGZO). Also, the first electrode 4 and the second electrode 5 may havea configuration in which a plurality of columnar metals are contained inthese transparent electrode materials.

The magnetic element 10 is manufactured, for example, by a laminatingstep, an annealing step, and a processing step for each layer. Eachlayer is formed by, for example, sputtering. Annealing is performed, forexample, at 250° C. or higher and 450° C. or lower. A laminated film isprocessed using, for example, photolithography and etching. Thelaminated film is a columnar magnetic element 10. The magnetic element10 may be a cylindrical element or a prismatic element. For example, theshortest width of the magnetic element 10 when viewed from the zdirection may be 10 nm or more and 2000 nm or less or 30 nm or more and500 nm or less. In the above steps, the magnetic element 10 is obtained.

The magnetic element 10 can be manufactured regardless of the materialconstituting the base. Thus, the receiving device 15 can be directlymanufactured on the circuit chip 35 without involving the adhesive layer70 or the like.

FIG. 6 shows an example of the magnetic element 10. It is only necessaryfor the magnetic element to have a ferromagnet whose magnetization statevaries with radiation of light and have a resistance value that changesas the magnetization state changes. For example, an anisotropicmagnetoresistance (AMR) effect element, a colossal magnetoresistance(CMR) effect element, and the like in addition to the above-mentionedtunnel magnetoresistance effect element or giant magnetoresistanceeffect element can be used for the magnetic element.

Next, some examples of the operation of the magnetic element 10 will bedescribed. The first ferromagnetic layer 1 is irradiated with lightwhose light intensity changes. The resistance value of the magneticelement 10 in the z direction changes when the first ferromagnetic layer1 is irradiated with light. An output voltage from the magnetic element10 changes when the first ferromagnetic layer 1 is irradiated withlight. In the first operation example, the case where the intensities ofthe light applied to the first ferromagnetic layer 1 are two levels of afirst intensity and a second intensity will be described. The intensityof light of the second intensity is set to be greater than the intensityof light of the first intensity. The first intensity may correspond tothe case where the intensity of light applied to the first ferromagneticlayer 1 is zero.

FIGS. 7 and 8 are diagrams for describing a first operation example ofthe magnetic element 10 according to the first embodiment. FIG. 7 is adiagram for describing a first mechanism of the first operation exampleand FIG. 8 is a diagram for describing a second mechanism of the firstoperation example. In the upper graphs of FIGS. 7 and 8, the verticalaxis represents an intensity of light with which the first ferromagneticlayer 1 is irradiated and the horizontal axis represents time. In thelower graphs of FIGS. 7 and 8, the vertical axis represents a resistancevalue of the magnetic element 10 in the z direction and the horizontalaxis represents time.

First, in a state in which the first ferromagnetic layer 1 is irradiatedwith light of the first intensity (hereinafter called an initial state),magnetization M1 of the first ferromagnetic layer 1 is parallel tomagnetization M2 of the second ferromagnetic layer 2 and a resistancevalue of the magnetic element 10 in the z direction is a firstresistance value R₁. The resistance value of the magnetic element 10 inthe z direction is obtained by causing a sense current is to flowthrough the magnetic element 10 in the z direction to generate a voltageacross both ends of the magnetic element 10 and using Ohm's law from avoltage value. An output voltage from the magnetic element 10 isgenerated between the first electrode 4 and the second electrode 5. Inthe case of the example shown in FIG. 7, the sense current Is flows in adirection from the first ferromagnetic layer 1 to the secondferromagnetic layer 2. By causing the sense current Is to flow in theabove direction, a spin transfer torque in a direction, which is thesame as that of the magnetization M2 of the second ferromagnetic layer2, acts on the magnetization M1 of the first ferromagnetic layer 1, andthe magnetization M1 becomes parallel to the magnetization M2 in theinitial state. Also, by causing the sense current Is to flow in theabove direction, it is possible to prevent the magnetization M1 of thefirst ferromagnetic layer 1 from being inverted during operation.

Next, the intensity of the light applied to the first ferromagneticlayer 1 changes from the first intensity to the second intensity. Thesecond intensity is greater than the first intensity and themagnetization M1 of the first ferromagnetic layer 1 changes from theinitial state. The state of the magnetization M1 of the firstferromagnetic layer 1 in the state in which the first ferromagneticlayer 1 is not irradiated with light is different from the state of themagnetization M1 of the first ferromagnetic layer 1 in the secondintensity. The state of the magnetization M1 is, for example, a tiltangle with respect to the z direction, a magnitude, or the like.

For example, as shown in FIG. 7, when the intensity of the light appliedto the first ferromagnetic layer 1 changes from the first intensity tothe second intensity, the magnetization M1 is tilted in the z direction.Also, for example, as shown in FIG. 8, when the intensity of the lightapplied to the first ferromagnetic layer 1 changes from the firstintensity to the second intensity, the magnitude of the magnetization M1becomes small. For example, when the magnetization M1 of the firstferromagnetic layer 1 is tilted in the z direction due to theirradiation intensity of light, a tilt angle is larger than 0° andsmaller than 90°.

When the magnetization M1 of the first ferromagnetic layer 1 changesfrom the initial state, the resistance value of the magnetic element 10in the z direction is a second resistance value R₂. The secondresistance value R₂ is larger than the first resistance value R₁. Thesecond resistance value R₂ is between a resistance value when themagnetization M1 is parallel to the magnetization M2 (the firstresistance value R₁) and a resistance value when the magnetization M1 isantiparallel to the magnetization M2.

In the case shown in FIG. 7, a spin transfer torque in a direction,which is the same as that of the magnetization M2 of the secondferromagnetic layer 2, acts on the magnetization M1 of the firstferromagnetic layer 1. Therefore, the magnetization M1 tries to returnto a state in which the magnetization M1 is parallel to themagnetization M2 and the magnetic element 10 returns to the initialstate when the intensity of the light applied to the first ferromagneticlayer 1 changes from the second intensity to the first intensity. In thecase shown in FIG. 8, when the intensity of the light applied to thefirst ferromagnetic layer 1 returns to the first intensity, themagnitude of the magnetization M1 of the first ferromagnetic layer 1returns to the original magnitude and the magnetic element 10 returns tothe initial state. In either case, the resistance value of the magneticelement 10 in the z direction returns to the first resistance value R₁.That is, when the intensity of the light applied to the firstferromagnetic layer 1 changes from the second intensity to the firstintensity, the resistance value of the magnetic element 10 in the zdirection changes from the second resistance value R₂ to the firstresistance value R₁.

The resistance value of the magnetic element 10 in the z directionchanges in correspondence with a change in the intensity of the lightapplied to the first ferromagnetic layer 1. The output voltage from themagnetic element 10 changes in correspondence with a change in theintensity of the light applied to the first ferromagnetic layer 1. Thatis, the magnetic element 10 can convert a change in the intensity of theapplied light into a change in the output voltage. That is, the magneticelement 10 can convert the received optical signal into an electricalsignal. The output voltage from the magnetic element 10 is sent to theintegrated circuit 36 and, for example, the integrated circuit 36processes the signal when the output voltage from the magnetic element10 is greater than or equal to a threshold value as a first signal (forexample, “1”) and processes the signal when the output voltage from themagnetic element 10 is less than the threshold value as a second signal(for example, “0”).

Although the case where the magnetization M1 is parallel to themagnetization M2 in the initial state has been described as an examplehere, the magnetization M1 may be antiparallel to the magnetization M2in the initial state. In this case, the resistance value of the magneticelement 10 in the z direction decreases as the state of themagnetization M1 changes (for example, as the change in the angle of themagnetization M1 increases from the initial state). When the initialstate is the case where the magnetization M1 is antiparallel to themagnetization M2, that the sense current Is may flow in a direction fromthe second ferromagnetic layer 2 to the first ferromagnetic layer 1. Bycausing the sense current Is to flow in the above direction, a spintransfer torque in a direction opposite to that of the magnetization M2of the second ferromagnetic layer 2 acts on the magnetization M1 of thefirst ferromagnetic layer 1 and the magnetization M1 becomesantiparallel to the magnetization M2 in the initial state.

In the first operation example, the case where the light applied to thefirst ferromagnetic layer 1 has two levels of the first intensity andthe second intensity has been described as an example, but in the secondoperation example, the case where the intensity of the light applied tothe first ferromagnetic layer 1 changes at multiple levels or in ananalog manner will be described.

FIGS. 9 and 10 are diagrams for describing a second operation example ofthe magnetic element 10 according to the first embodiment. FIG. 9 is adiagram for describing a first mechanism of the second operation exampleand FIG. 10 is a diagram for describing a second mechanism of the secondoperation example. In the upper graphs of FIGS. 9 and 10, the verticalaxis represents an intensity of light applied to the first ferromagneticlayer 1 and the horizontal axis represents time. In the lower graphs ofFIGS. 9 and 10, the vertical axis represents a resistance value of themagnetic element 10 in the z direction and the horizontal axisrepresents time.

In the case of FIG. 9, when the intensity of the light applied to thefirst ferromagnetic layer 1 increases, the magnetization M1 of the firstferromagnetic layer 1 is tilted from the initial state due to externalenergy generated by the radiation of the light. An angle between thedirection of the magnetization M1 of the first ferromagnetic layer 1when the first ferromagnetic layer 1 is not irradiated with light andthe direction of the magnetization M1 when the first ferromagnetic layer1 is irradiated with light is greater than 0° and less than 90°.

When the magnetization M1 of the first ferromagnetic layer 1 is tiltedfrom the initial state, the resistance value of the magnetic element 10in the z direction changes. For example, the resistance value of themagnetic element 10 in the z direction changes to the second resistancevalue R₂, a third resistance value R₃, or a fourth resistance value R₄in accordance with the tilt of the magnetization M1 of the firstferromagnetic layer 1. The resistance value increases in the order ofthe first resistance value R₁, the second resistance value R₂, the thirdresistance value R₃, and the fourth resistance value R₄. That is, theoutput voltage from the magnetic element 10 changes from a first voltagevalue to a second voltage value, a third voltage value, or a fourthvoltage value in accordance with the tilt of the magnetization M1 of thefirst ferromagnetic layer 1. The output voltage increases in the orderof the first voltage value, the second voltage value, the third voltagevalue, and the fourth voltage value.

The resistance value of the magnetic element 10 in the z directionchanges when the intensity of the light applied to the firstferromagnetic layer 1 has changed. The output voltage from the magneticelement 10 changes when the intensity of the light applied to the firstferromagnetic layer 1 has changed. For example, if the first voltagevalue is defined as “0,” the second voltage value is defined as “1,” thethird voltage value is defined as “2,” and the fourth voltage value isdefined as “3,” the magnetic element 10 can output information aboutfour values. Although the case where four values are read is shown as anexample here, the number of values to be read can be freely designed bysetting the threshold value of the output voltage. Also, the magneticelement 10 may output an analog value as it is.

Likewise, in the case of FIG. 10, when the intensity of the lightapplied to the first ferromagnetic layer 1 increases, the magnitude ofthe magnetization M1 of the first ferromagnetic layer 1 decreases fromthe initial state due to external energy generated by the radiation ofthe light. When the magnetization M1 of the first ferromagnetic layer 1decreases from the initial state, the resistance value of the magneticelement 10 in the z direction changes. For example, the resistance valueof the magnetic element 10 in the z direction changes to the secondresistance value R₂, the third resistance value R₃, or the fourthresistance value R₄ in accordance with the magnitude of themagnetization M1 of the first ferromagnetic layer 1. That is, the outputvoltage from the magnetic element 10 changes from the first voltagevalue to the second voltage value, the third voltage value, or thefourth voltage value in accordance with the magnitude of themagnetization M1 of the first ferromagnetic layer 1. Therefore, as inthe case of FIG. 9, the magnetic element 10 can output a differencebetween the above output voltages as multi-valued or analog data.

Also, in the case of the second operation example, as in the case of thefirst operation example, when the intensity of the light applied to thefirst ferromagnetic layer 1 returns to the first intensity, themagnetization M1 of the first ferromagnetic layer 1 returns to theoriginal state and the magnetic element 10 returns to the initial state.

Although the case where the magnetization M1 is parallel to themagnetization M2 in the initial state has been described as an examplehere, the magnetization M1 may also be antiparallel to the magnetizationM2 in the initial state in the second operation example.

Also, in the first operation example and the second operation example,the case where the magnetization M1 is parallel or antiparallel to themagnetization M2 in the initial state is exemplified, but themagnetization M1 may be orthogonal to the magnetization M2 in theinitial state. For example, the above case corresponds to the case wherethe first ferromagnetic layer 1 is an in-plane magnetization film wherethe magnetization M1 is oriented in any direction of the xy plane andthe second ferromagnetic layer 2 is a perpendicular magnetization filmwhere the magnetization M2 is oriented in the z direction. Themagnetization M1 is oriented in any direction within the xy plane due tomagnetic anisotropy and the magnetization M2 is oriented in the zdirection, so that the magnetization M1 is orthogonal to themagnetization M2 in the initial state.

FIGS. 11 and 12 are diagrams for describing another example of thesecond operation example of the magnetic element 10 according to thefirst embodiment. The flow direction of the sense current Is applied tothe magnetic element 10 is different between FIGS. 11 and 12. In FIG.11, the sense current Is flows from the first ferromagnetic layer 1 tothe second ferromagnetic layer 2. In FIG. 12, the sense current Is flowsfrom the second ferromagnetic layer 2 to the first ferromagnetic layer1.

In both cases of FIGS. 11 and 12, a spin transfer torque acts on themagnetization M1 in the initial state due to the sense current Isflowing through the magnetic element 10. In the case of FIG. 11, thespin transfer torque acts so that the magnetization M1 is parallel tothe magnetization M2 of the second ferromagnetic layer 2. In the case ofFIG. 12, the spin transfer torque acts so that the magnetization M1 isantiparallel to the magnetization M2 of the second ferromagnetic layer2. In both cases of FIGS. 11 and 12, the effect of magnetic anisotropyon the magnetization M1 is greater than the effect of the spin transfertorque in the initial state, so that the magnetization M1 is directed inany direction within the xy plane.

When the intensity of the light applied to the first ferromagnetic layer1 increases, the magnetization M1 of the first ferromagnetic layer 1 istilted from the initial state due to the external energy generated bythe radiation of the light. This is because a sum of the effect ofradiation of light applied to the magnetization M1 and the effect of thespin transfer torque is greater than the effect of magnetic anisotropyrelated to the magnetization M1. When the intensity of the light appliedto the first ferromagnetic layer 1 increases, the magnetization M1 inthe case of FIG. 11 tilts to be parallel to the magnetization M2 of thesecond ferromagnetic layer 2 and the magnetization M1 in the case ofFIG. 12 tilts to be antiparallel to the magnetization M2 of the secondferromagnetic layer 2. Because the direction of the spin transfer torqueacting on the magnetization M1 is different, the tilt directions of themagnetization M1 in FIGS. 11 and 12 are different.

When the intensity of the light applied to the first ferromagnetic layer1 increases, the resistance value of the magnetic element 10 in the zdirection decreases in the case of FIG. 11 and the resistance value ofthe magnetic element 10 in the z direction increases in the case of FIG.12. That is, when the intensity of the light applied to the firstferromagnetic layer 1 increases, the output voltage from the magneticelement 10 decreases in the case of FIG. 11 and the output voltage ofthe magnetic element 10 increases in the case of FIG. 12.

When the intensity of the light applied to the first ferromagnetic layer1 returns to the first intensity, the state of the magnetization M1 ofthe first ferromagnetic layer 1 returns to the original state due to theeffect of magnetic anisotropy on the magnetization M1. As a result, themagnetic element 10 returns to the initial state.

Although the first ferromagnetic layer 1 is an in-plane magnetizationfilm and the second ferromagnetic layer 2 is a perpendicularmagnetization film here, a relationship therebetween may be reversed.That is, in the initial state, the magnetization M1 may be oriented inthe z direction and the magnetization M2 may be oriented in anydirection within the xy plane.

As described above, the receiving device 15 receives an optical signaland converts the received optical signal into an electrical signal bythe magnetic element 10.

FIG. 13 is a plan view of the optical modulation element 21 of thetransmission device 25 according to the first embodiment when viewedfrom the z direction. FIG. 14 is a cross-sectional view of the opticalmodulation element 21 according to the first embodiment. FIG. 14 is across section taken along the line A-A of FIG. 13. The opticalmodulation element 21 converts an electrical signal into an opticalsignal. The optical modulation element 21 is an example of a modulatedlight output element. The optical modulation element 21 shown in FIGS.13 and 14 is an example of the optical modulation element and aconfiguration of the optical modulation element is not limited to theabove example.

The optical modulation element 21 includes a substrate 22, a coatinglayer 23, a waveguide 26, and an electrode 27.

The substrate 22 includes, for example, aluminum oxide. The substrate 22is, for example, sapphire. The coating layer 23 is, for example, SiO₂,Al₂O₃, MgF₂, La₂O₃, ZnO, HfO₂, MgO, Y₂O₃, CaF₂, In₂O₃, or a mixturethereof.

The waveguide 26 has, for example, an input waveguide 26A, a branchportion 26B, a first waveguide 26C, a second waveguide 26D, a couplingportion 26E, and an output waveguide 26F.

The input waveguide 26A has an input end to which input light L_(in) isinput and is connected to the branch portion 26B. The branch portion 26Bis between the input waveguide 26A and the first waveguide 26C and thesecond waveguide 26D. The input light L_(in) is input from the outside.The input light L_(in) is, for example, laser light.

For example, the first waveguide 26C and the second waveguide 26D extendin the x direction. Lengths of the first waveguide 26C and the secondwaveguide 26D in the x direction are, for example, substantially thesame.

The coupling portion 26E is positioned between the first waveguide 26Cand the second waveguide 26D and the output waveguide 26F. The outputwaveguide 26F is connected to the coupling portion 26E and has an outputend from which output light L_(out) is output.

As shown in FIG. 14, the first waveguide 26C and the second waveguide26D include a part of a slab 28 and a ridge-shaped portion 28P. The slab28 spreads on the substrate 22. The ridge-shaped portion 28P projectsfrom the upper surface of the slab 28. The slab 28 increases thestrength of an electric field applied to the waveguide 26.

The slab 28 and the ridge-shaped portion 28P include lithium niobate asa main component. Therefore, the waveguide 26 includes lithium niobateas a main component. Some elements of lithium niobate may be replacedwith other elements. The waveguide 26 is covered with, for example, thecoating layer 23. The slab 28 and the ridge-shaped portion 28P may bemade of materials other than lithium niobate. For example, the slab 28and the ridge-shaped portion 28P may be silicon or silicon oxide towhich germanium oxide is added and the coating layer 23 may be siliconoxide. The input waveguide 26A, the branch portion 26B, the couplingportion 26E, and the output waveguide 26F also have configurationssimilar to those of the first waveguide 26C and the second waveguide26D.

The electrode 27 includes, for example, an electrode 27A, an electrode27B, and an electrode 27C. The electrodes 27A and 27B are at positionswhere an electric field can be applied to at least a part of thewaveguide 26. An electric field can be applied from the electrode 27A tothe first waveguide 26C. An electric field can be applied from theelectrode 27B to the second waveguide 26D. The electrode 27A is, forexample, above the first waveguide 26C. The electrode 27B is, forexample, above the second waveguide 26D. The electrode 27C is, forexample, on the sides of the electrode 27A and the electrode 27B.

The electrodes 27A and 27B are connected to the integrated circuit 36(the electronic component 32 or the wiring 33) of the circuit chip 35.The electrode 27C is connected to a reference potential. The referencepotential is, for example, a ground potential.

A voltage is applied from the integrated circuit 36 to the electrode27A. The integrated circuit 36 applies a modulated voltage to theelectrode 27A. A voltage is applied from the integrated circuit 36 tothe electrode 27B. The integrated circuit 36 applies a modulated voltageto the electrode 27B. The voltage applied to the electrode 27A and thevoltage applied to the electrode 27B can be controlled individually.

Input light L_(in) input from the input waveguide 26A branches into thefirst waveguide 26C and the second waveguide 26D and propagates. A phasedifference between light propagating through the first waveguide 26C andlight propagating through the second waveguide 26D is zero at the timeof branching.

When a voltage is applied between the electrode 27A and the electrode27C, an electric field is applied to the first waveguide 26C and arefractive index of the first waveguide changes due to anelectro-optical effect. When a voltage is applied between the electrode27B and the electrode 27C, an electric field is applied to the secondwaveguide 26D and a refractive index of the second waveguide 26D changesdue to the electro-optical effect.

If the refractive indices of the first waveguide 26C and the secondwaveguide 26D are different, a phase difference occurs between the lightpropagating through the first waveguide 26C and the light propagatingthrough the second waveguide 26D. The light propagating through thefirst waveguide 26C and the second waveguide 26D merges at the outputwaveguide 26F and is output from the optical modulation element 21 asoutput light L_(out).

The output light L_(out) is light obtained by superposing the lightpropagating through the first waveguide 26C onto the light propagatingthrough the second waveguide 26D. An intensity of the output lightL_(out) varies with the phase difference between the light propagatingthrough the first waveguide 26C and the light propagating through thesecond waveguide 26D. For example, when the phase difference is an evenmultiple of π, the above types of light strengthen each other and theintensity of the output light L_(out) increases, and when the phasedifference is an odd multiple of π, the above types of light weaken eachother and the intensity of the output light L_(out) decreases. Based onthis principle, the optical modulation element 21 modulates the inputlight L_(in) into the output light L_(out) in accordance with theelectrical signal from the integrated circuit 36. The transmissiondevice 25 transmits the output light L_(out) after the modulation by theoptical modulation element 21 as an optical signal.

In the transceiver device 100 according to the first embodiment, themagnetic element 10 configured to convert a received optical signal intoan electrical signal and the optical modulation element 21 configured tooutput an optical signal, which is modulated light, are electricallyconnected to the integrated circuit 36 configured to control themagnetic element 10 and the optical modulation element 21 and themagnetic element 10 and the optical modulation element 21 are arrangedon the circuit chip 35 in the z direction. Thereby, the transceiverdevice 100 according to the first embodiment can be miniaturized. Also,the transceiver device 100 according to the first embodiment can betreated as one packaged electronic component and can be easily connectedto another component such as the fiber 202.

Also, the magnetic element 10 can be manufactured regardless of thematerial constituting the base and can be manufactured on the circuitchip 35 without using the adhesive layer 70 or the like. Therefore, inthe transceiver device 100 according to the first embodiment, themagnetic element 10 can be easily arranged on the circuit chip 35 in thez direction and the miniaturization can be easily performed.

Second Embodiment

FIG. 15 is a cross-sectional view of a transceiver device 101 accordingto a second embodiment. In the second embodiment, components similar tothose in the first embodiment are designated by the same reference signsand the description thereof will be omitted.

The transceiver device 101 is different from the transceiver device 100according to the first embodiment in the lamination order of a receivingdevice 15, a transmission device 25, and a circuit chip 35. In thetransceiver device 101, lamination is achieved in the order of thecircuit chip 35, the receiving device 15, and the transmission device25. The receiving device 15 and the transmission device 25 are on afirst surface 35S1 side of the circuit chip 35. A magnetic element 10and an optical modulation element 21 are on the first surface 35S1 sideof the circuit chip 35. The receiving device 15 is between the circuitchip 35 and the transmission device 25 in a z direction. A position ofthe magnetic element 10 in the z direction is between a position of thecircuit chip 35 in the z direction and a position of the opticalmodulation element 21 in the z direction.

A waveguide 11 is on one surface of the receiving device 15. Thewaveguide 11 is, for example, between the receiving device 15 and thetransmission device 25. One end of the waveguide 11 is in a travelingdirection of light output from an end of a first fiber 130. The lightincluding a signal output from the end of the first fiber 130 propagatesthrough the waveguide 11 and is applied to the magnetic element 10.

The transmission device 25 is attached to the receiving device 15 by,for example, an adhesive layer 70. In the example shown in FIG. 15, asubstrate 22 of the transmission device 25 is attached to the waveguide11 side of the receiving device 15 via the adhesive layer 70. Anintegrated circuit 36 of the circuit chip 35 and the optical modulationelement 21 of the transmission device 25 are electrically connected viathrough wiring 60. For example, the through wiring 60 passes throughinsulating layers (for example, the substrate 22 having insulatingproperties, the adhesive layer 70, an insulating layer 12 and aninsulating layer 34) between the optical modulation element 21 and theintegrated circuit 36 in the z direction. The through wiring 60 connectsthe optical modulation element 21 to the integrated circuit 36. Theoptical modulation element 21 and the integrated circuit 36 may beelectrically connected to each other via a bump between the transmissiondevice 25 and the circuit chip 35, as in the first embodiment. In thiscase, the bump between the transmission device 25 and the circuit chip35 is provided between the transmission device 25 and the receivingdevice 15 sandwiching the adhesive layer 70.

The transceiver device 101 according to the second embodiment haseffects similar to those of the transceiver device 100 according to thefirst embodiment.

Third Embodiment

FIG. 16 is a cross-sectional view of a transceiver device 102 accordingto a third embodiment. In the third embodiment, components similar tothose in the first embodiment are designated by the same reference signsand the description thereof will be omitted.

The transceiver device 102 is different from the transceiver device 100according to the first embodiment in the lamination order of a receivingdevice 15, a transmission device 25, and a circuit chip 35. In thetransceiver device 102, lamination is achieved in the order of thecircuit chip 35, the transmission device 25, and the receiving device15. The receiving device 15 and the transmission device 25 are on asecond surface 35S2 side of the circuit chip 35. A magnetic element 10and an optical modulation element 21 are on the second surface 35S2 sideof the circuit chip 35. The transmission device 25 is positioned betweenthe circuit chip 35 and the receiving device 15 in a z direction. Aposition of the optical modulation element 21 in the z direction isbetween a position of the circuit chip 35 in the z direction and aposition of the magnetic element 10 in the z direction.

The transmission device 25 is attached to the circuit chip 35 by, forexample, an adhesive layer 70. In the example shown in FIG. 16, asubstrate 22 of the transmission device 25 is attached to a substrate 31of the circuit chip 35 via the adhesive layer 70. An integrated circuit36 of the circuit chip 35 and the optical modulation element 21 of thetransmission device 25 are electrically connected via through wiring 60.For example, the through wiring 60 passes through insulating layers (forexample, the substrate 22 having insulating properties, the adhesivelayer 70, and the insulating substrate 31 having insulating properties)between the optical modulation element 21 and the integrated circuit 36in the z direction. The through wiring 60 connects the opticalmodulation element 21 and the integrated circuit 36. The opticalmodulation element 21 and the integrated circuit 36 may be electricallyconnected via a bump between the transmission device 25 and the circuitchip 35, as in the first embodiment. In this case, the bump between thetransmission device 25 and the circuit chip 35 is provided between thesubstrate 22 and the substrate 31 sandwiching the adhesive layer 70.

For example, the magnetic element 10 is provided on a coating layer 23of the transmission device 25. The integrated circuit 36 of the circuitchip 35 and the magnetic element 10 of the receiving device 15 areelectrically connected via through wiring 50. For example, the throughwiring 50 passes through insulating layers (for example, an insulatinglayer 12, the coating layer 23, the substrate 22, the adhesive layer 70,and an insulating layer 34) between the magnetic element 10 and theintegrated circuit 36 in the z direction. The through wiring 50 connectsthe magnetic element 10 to the integrated circuit 36.

The transceiver device 102 according to the third embodiment has effectssimilar to those of the transceiver device 100 according to the firstembodiment.

Fourth Embodiment

FIG. 17 is a cross-sectional view of a transceiver device 103 accordingto a fourth embodiment. FIG. 18 is a plan view of the transceiver device103 according to the fourth embodiment. In the fourth embodiment,components similar to those in the first embodiment are designated bythe same reference signs and the description thereof will be omitted.

The transceiver device 103 is different from the transceiver device 100according to the first embodiment in the arrangement of a receivingdevice 15 and a transmission device 25. The receiving device 15 and thetransmission device 25 are on a first surface 35S1 side of a circuitchip 35. A magnetic element 10 and an optical modulation element 21 areon the first surface 35S1 side of the circuit chip 35. The receivingdevice 15 and the transmission device 25 are arranged, for example, onthe first surface 35S1 of the circuit chip 35. The receiving device 15and the transmission device 25 are positioned at positions where they donot overlap each other when viewed from a z direction. The magneticelement 10 and the optical modulation element 21 are arranged not tooverlap each other when viewed from the z direction.

The transmission device 25 is attached to the circuit chip 35 by, forexample, an adhesive layer 70. In the example shown in FIG. 17, asubstrate 22 of the transmission device 25 is attached to an insulatinglayer 34 of the circuit chip 35 via the adhesive layer 70. An integratedcircuit 36 of the circuit chip 35 and the optical modulation element 21of the transmission device 25 are electrically connected via throughwiring 60. For example, the through wiring 60 passes through insulatinglayers (for example, a substrate 22 having insulating properties, theadhesive layer 70, and an insulating layer 34) between the opticalmodulation element 21 and the integrated circuit 36 in the z direction.The through wiring 60 connects the optical modulation element 21 and theintegrated circuit 36. The optical modulation element 21 and theintegrated circuit 36 may be electrically connected via a bump betweenthe transmission device 25 and the circuit chip 35, as in the firstembodiment. In this case, the bump between the transmission device 25and the circuit chip 35 is provided between the substrate 22 and theinsulating layer 34 sandwiching the adhesive layer 70.

The transceiver device 103 according to the fourth embodiment haseffects similar to those of the transceiver device 100 according to thefirst embodiment.

Fifth Embodiment

FIG. 19 is a cross-sectional view of a transceiver device 104 accordingto a fifth embodiment. In the fifth embodiment, components similar tothose in the fourth embodiment are designated by the same referencesigns and the description thereof will be omitted.

A transceiver device 104 has a transmission device 40 instead of thetransmission device 25 of the transceiver device 103 of the fourthembodiment. The transmission device 40 includes a modulated light outputelement. The modulated light output element according to the fifthembodiment is an element that outputs modulated light according to aprocess of directly switching ON/OFF of an output of light by switchingON/OFF of a power supply. The modulated light output element accordingto the fifth embodiment is, for example, a laser diode, a light emittingdiode (LED), or the like. When a frequency of an optical signal outputfrom the transmission device 40 is about several MHz, the modulatedoptical output element, which directly switches ON/OFF, can alsosufficiently cope with the frequency.

The transceiver device 104 according to the fifth embodiment has effectssimilar to those of the transceiver device 100 according to the firstembodiment.

Sixth Embodiment

FIG. 20 is a cross-sectional view of a transceiver device 105 accordingto a sixth embodiment. FIG. 21 is a plan view of the transceiver device105 according to the sixth embodiment. In the sixth embodiment,components similar to those in the fourth embodiment are designated bythe same reference signs and the description thereof will be omitted.

The transceiver device 105 further includes a light source 80 withrespect to the transceiver device 103 of the fourth embodiment. Thelight source 80 is arranged on a circuit chip in a z direction. Thelight source 80 is on a first surface 35S1 side of a circuit chip 35.The light source 80 is arranged, for example, on the first surface 35S1of the circuit chip 35. A receiving device 15, a transmission device 25,and the light source 80 are positioned at positions where they do notoverlap each other when viewed from the z direction. A magnetic element10, an optical modulation element 21, and the light source 80 arearranged not to overlap each other when viewed from the z direction.

The light source 80 outputs input light input to an optical modulationelement 21. The light source 80 is positioned on the side of the opticalmodulation element 21. The light source 80 is, for example, a laserdiode.

The transceiver device 105 according to the sixth embodiment includingthe light source 80 is packaged. The transceiver device 105 according tothe sixth embodiment has effects similar to those of the transceiverdevice 100 according to the first embodiment.

FIG. 20 shows an example in which the light source 80 is incorporatedinto the transceiver device 103 according to the fourth embodiment, butthe light source 80 may be incorporated into the transceiver devices 100to 102 according to the first to third embodiments. The light source 80may be arranged on a side of a surface that is the same as the surfaceof the circuit chip 35 on which the optical modulation element 21 isarranged. FIG. 22 is a modified example of the transceiver deviceaccording to the fifth embodiment. A transceiver device 105A shown inFIG. 22 is an example in which the light source 80 is incorporated inthe transceiver device 100 according to the first embodiment. In theexample shown in FIG. 22, the light source 80 is on a second surface35S2 side of the circuit chip 35.

Seventh Embodiment

FIG. 23 is a cross-sectional view of a transceiver device 106 accordingto a seventh embodiment. FIG. 24 is a plan view of the transceiverdevice 106 according to the seventh embodiment. In the seventhembodiment, components similar to those in the first embodiment aredesignated by the same reference signs and the description thereof willbe omitted.

The transceiver device 106 includes a receiving device 15, atransmission device 25, a circuit chip 35, a light source 80, and awiring chip 90. The receiving device 15, the transmission device 25, thelight source 80, and the circuit chip 35 are on a first surface 90S1side of the wiring chip 90. A magnetic element 10 and an opticalmodulation element 21 are on the first surface 90S1 side of the wiringchip 90. The receiving device 15, the transmission device 25, the lightsource 80, and the circuit chip 35 are arranged on the first surface90S1 of the wiring chip 90. The receiving device 15, the transmissiondevice 25, the light source 80, and the circuit chip 35 are positionedat positions where they do not overlap each other when viewed from a zdirection. The magnetic element 10, the optical modulation element 21,and the circuit chip 35 are arranged not to overlap each other whenviewed from the z direction.

The wiring chip 90 includes wirings 91 and an insulating layer 92. Eachof the magnetic element 10, the optical modulation element 21, the lightsource 80, and an integrated circuit 36 of the circuit chip 35 iselectrically connected to the wiring chip 90 by through wiring 93. Thewiring 91 and the through wiring 93 electrically connect each of themagnetic element 10, the optical modulation element 21, and the lightsource 80 to the integrated circuit 36 of the circuit chip 35. Themagnetic element 10 is connected to any wiring 91. The opticalmodulation element 21 is connected to any wiring 91. The integratedcircuit 36 (an electronic component 32 or a wiring 33) is connected toany wiring 91. The magnetic element 10, the optical modulation element21, and the light source 80 are controlled by the integrated circuit 36of the circuit chip 35.

The transceiver device 106 according to the seventh embodiment haseffects similar to those of the transceiver device 100 according to thefirst embodiment. Also, the transceiver device 106 according to theseventh embodiment can be packaged after each element is manufacturedseparately. Optimization of each element is easy.

The present disclosure is not limited to the above-described embodimentsand modified examples and various modifications and changes can be madewithin the scope of the subject matter of the present disclosuredescribed within the scope of the claims. For example, the featureconfigurations of the above-described embodiment and modified examplesmay be combined.

For example, although an example in which the modulated light outputelement configured to switch ON/OFF of an output of light directly isused instead of the optical modulation element 21 of the fourthembodiment has been described in the fifth embodiment, the modulatedlight output element configured to directly switch ON/OFF of an outputof light may be used instead of the optical modulation element 21 of thefirst to third embodiments. Also, the modulated light output elementconfigured to directly switch ON/OFF of an output of light may be usedinstead of the optical modulation elements 21 and the light sources 80of the sixth and seventh embodiments.

Although examples in which the transceiver devices according to thefirst to seventh embodiments are applied to the communication system 200show in FIG. 1 have been described above, the communication system isnot limited thereto.

For example, FIG. 25 is a conceptual diagram of another example of thecommunication system. In a communication system 300 shown in FIG. 25,communication between two portable terminal devices 301 is performed.The portable terminal device 301 is, for example, a smartphone, atablet, or the like.

Each of the portable terminal devices 301 includes the above-describedtransceiver device 100. The transceiver device 100 may be one of thetransceiver devices 101 to 106 other than that of the first embodiment.An optical signal transmitted from the transmission device 25 of oneportable terminal device 301 is received by the receiving device 15 ofthe other portable terminal device 301. The light used fortransmission/reception between the portable terminal devices 301 is, forexample, visible light. Each receiving device 15 has a magnetic elementand the magnetic element converts an optical signal into an electricalsignal.

Also, for example, FIG. 26 is a conceptual diagram of another example ofthe communication system. In a communication system 310 shown in FIG.26, communication between a portable terminal device 301 and aninformation processing device 302 is performed. The informationprocessing device 302 is, for example, a personal computer.

The portable terminal device 301 includes a transceiver device 100 andthe information processing device 302 includes a receiving device 107.The transceiver device 100 may be one of the transceiver devices 101 to106 other than that of the first embodiment. The information processingdevice 302 may include any one of the transceiver devices 100 to 106instead of the receiving device 107. An optical signal transmitted froma transmission device 25 of the portable terminal device 301 is receivedby a receiving device 15 of the information processing device 302. Lightused for transmission/reception between the portable terminal device 301and the information processing device 302 is, for example, visiblelight. Each receiving device 15 has a magnetic element, and the magneticelement converts an optical signal into an electrical signal.

What is claimed is:
 1. A transceiver device comprising: a receivingdevice including a magnetic element having a first ferromagnetic layer,a second ferromagnetic layer, and a spacer layer sandwiched between thefirst ferromagnetic layer and the second ferromagnetic layer, whereinthe receiving device is configured to receive an optical signal; atransmission device including a modulated light output element, whereinthe transmission device is configured to transmit an optical signal; anda circuit chip including an integrated circuit electrically connected tothe magnetic element and the modulated light output element.
 2. Thetransceiver device according to claim 1, wherein the magnetic elementand the modulated light output element are arranged in a directionperpendicular to a surface of the circuit chip.
 3. The transceiverdevice according to claim 2, wherein a position of the circuit chip inthe direction is between a position of the magnetic element in thedirection and a position of the modulated light output element in thedirection.
 4. The transceiver device according to claim 2, wherein aposition of the magnetic element in the direction is between a positionof the modulated light output element in the direction and a position ofthe circuit chip in the direction.
 5. The transceiver device accordingto claim 2, wherein a position of the modulated light output element inthe direction is between a position of the magnetic element in thedirection and a position of the circuit chip in the direction.
 6. Thetransceiver device according to claim 2, wherein the magnetic elementand the modulated light output element are positioned on a first surfaceside of the circuit chip, and wherein the magnetic element and themodulated light output element do not overlap each other when viewedfrom the direction.
 7. The transceiver device according to claim 1,wherein the magnetic element and the integrated circuit are electricallyconnected via first through wiring that passes through an insulatinglayer between the magnetic element and the integrated circuit, andwherein the modulated light output element and the integrated circuitare electrically connected via second through wiring that passes throughan insulating layer between the modulated light output element and theintegrated circuit.
 8. The transceiver device according to claim 2,wherein the modulated light output element and the integrated circuitare electrically connected via a bump between the transmission deviceand the circuit chip.
 9. The transceiver device according to claim 1,further comprising: a wiring chip including wiring electricallyconnected to the magnetic element, the modulated light output elementand the integrated circuit, wherein the magnetic element, the modulatedlight output element, and the circuit chip are positioned on a firstsurface side of the wiring chip, and wherein the magnetic element, themodulated light output element, and the circuit chip do not overlap eachother when viewed from a direction perpendicular to a surface of thewiring chip.
 10. The transceiver device according to claim 1, whereinthe modulated light output element is an optical modulation element. 11.The transceiver device according to claim 10, wherein the opticalmodulation element includes a waveguide, and wherein the waveguideincludes lithium niobate.
 12. The transceiver device according to claim1, further comprising: an input portion configured to apply lightincluding a signal to the magnetic element; an output portion configuredto output light including a signal generated by the modulated lightoutput element; a first fiber configured to connect the input portion toan external portion; and a second fiber configured to connect the outputportion to an external portion.
 13. A transmission device comprising: amodulated light output element including a waveguide which includeslithium niobate; and a circuit chip including an integrated circuitelectrically connected to the modulated light output element.
 14. Thetransmission device according to claim 13, wherein the modulated lightoutput element and the integrated circuit are electrically connected viathrough wiring that passes through an insulating layer between themodulated light output element and the integrated circuit.
 15. Thetransmission device according to claim 13, wherein the modulated lightoutput element and the integrated circuit are electrically connected viaa bump between the modulated light output element and the circuit chip.